Members of the soon-to-be Trump administration are heading into battle this week, as a slew of confirmation hearings for the president-elect’s top Cabinet officials begin on Capitol Hill. They will be, in a sense, well-fortified.

That’s because the incoming commander-in-chief has the benefit of not only a Republican Senate majority intent on a swift process but also a simple 51-vote threshold requirement for confirming his executive appointments. For the latter, Donald Trump can thank former Sen. Harry Reid, who in 2013 led fellow Democrats in changing the chamber’s filibuster rules to prevent the minority party from blocking the president’s nominees (except for Supreme Court appointments).

But Senate Democrats aren’t submitting quietly to that reality. With virtually no recourse to block Trump’s designees outright, they first intend to delay the incoming administration from taking shape and thus forestall its plan to unravel much of the work of the outgoing one.

If they can’t prevent Trump from having his Dream Team of players, the opposition party aims to undermine some of the key ones, forcing the new president to spend his political capital defending them early on. The process could also reveal just how much Trump is willing to go to bat for his team.

Democrats have pushed for additional background information on nominees, such as the submission of tax returns, beyond the traditional paperwork, ethics review, and vetting by the FBI. They argue that Trump’s nominees are wealthier and have less experience in government than is typical, thus requiring greater financial disclosure. If that process unveils damaging details, Democrats believe their cause could be advanced.

In addition, they are seizing on concerns raised over the weekend by the Office of Government Ethics that some nominees’ hearings will begin without ethics reviews having been completed. “It has left some of the nominees with potentially unknown or unresolved ethics issues shortly before their scheduled hearings," wrote the OGE’s director, Walter Shaub, in a letter to Senate leaders, noting the apparently unprecedented nature of the situation. Shaub also said that the office had not received financial disclosure reports from some of the nominees. (The OGE came under fire in November for a series of unusual tweets, directed by Shaub, urging Trump to divest from his business interests.)

The Trump transition team disputed Shaub's assertion that past nominees have cleared the ethics review before their hearings, pointing to such an occurrence under President George W. Bush. In a statement, a Trump spokesperson said it is “disappointing some have chosen to politicize the [transition] process in order to distract from important issues facing our country.”

The Democrats’ battlefield is large, encompassing as many as eight designees. Among the top targets are Rex Tillerson for secretary of state, Tom Price as head of Health and Human Services, Jeff Sessions for attorney general and Steven Mnuchin for Treasury secretary. Those nominees reflect some of the new administration’s top priorities and their hearings will touch upon some key issues of the day, including Russian hacking, the repeal and replacement of Obamacare, immigration, and the economy. Others on the target list include Betsy DeVos for education secretary, Andy Puzder for labor secretary, Scott Pruitt as head of the Environmental Protection Agency, and Mick Mulvaney for the Office of Management and Budget.

“The outcome may be clear but it could take a long time to get there,” says Max Stier of the nonpartisan Partnership for Public Service, noting the deliberative and often slow-moving nature of the Senate. “If you don’t have a good operating rhythm with the opposing party, they can slow things down, and [the president could have] a much diminished ability to get things done.”

In some rare cases, Democrats could get a bit of help from the incoming president’s party. A handful of Republicans have concerns about Tillerson, given his business ties to Russia as head of ExxonMobil. Sen. John McCain, for example, recently said that he’d support Tillerson when “pigs fly.” But Senate Majority Leader Mitch McConnell is helping the new administration minimize the public scrutiny by packing the hearing schedule. There will be five hearings on Wednesday alone, for example -- not coincidentally the day of Trump’s first press conference since late July.

Multiple committee rooms will see a flurry of activity on Jan. 11, beginning with Tillerson’s appearance before the Foreign Relations Committee. Others to be considered that day, with some overlapping, include DeVos, Rep. Mike Pompeo for CIA director, and Elaine Chao for transportation secretary.

But the process officially begins Tuesday. And first up is Trump’s closest ally, Sen. Jeff Sessions, who has an advantage that nominees coming from the private sector don’t: He serves on the Judiciary Committee, which will oversee his confirmation process. (The hearing to consider Gen. John Kelly as head of Homeland Security takes place Tuesday afternoon.)

Democrats are seizing on Sessions’ criticisms of the Voting Rights Act and the same committee’s rejection of his 1986 nomination to a federal judgeship after highlighting his past racially charged remarks. The American Civil Liberties Union has launched a campaign against the nominee. A group of 1,100 law professors from across the country have signed a letter opposing the confirmation of the Alabama lawmaker, who was one of the earliest backers of Trump’s unlikely presidential bid.

But supporters have come to his defense. The Judicial Crisis Network launched a six-figure ad blitz airing in Missouri, Indiana, and North Dakota -- all states where Trump won and where Democratic senators are up for re-election in 2018 -- as well as in Washington, D.C. The ads will run for the duration of the confirmation process.

Those midterm elections, though nearly two years off, could play a role in the confirmation process, as dozens of Democrats from Trump states may face consequences if they defy the incoming president on certain issues. “All eyes will be on them later,” says Sarah Isgur Flores, a Republican strategist directing communications for Sessions during the confirmation process. “The ads kind of write themselves.”

One of those Democrats is Joe Manchin, who faces re-election in two years in West Virginia, a state Trump won by 42 percentage points. Manchin has said he would support Sessions. He could also come to Republicans’ rescue regarding Tillerson. And Manchin has had kind words for EPA nominee Pruitt, even though his fellow Democrats oppose the Oklahoma attorney general, who has been skeptical about climate change.

“We both come from energy-producing states and have a great deal in common,” Manchin said in a statement released by the Trump transition team.

Other Democrats may be inclined to keep their powder dry, saving it for Trump’s nominee for the Supreme Court. Senate Minority Leader Chuck Schumer has already pledged to “fight tooth and nail” against any high court nominee he considers outside the mainstream. And Democrats will have a better opportunity to block that pick, as the filibuster limitations do not apply to Supreme Court nominees and will thus require a 60-vote threshold for confirmation.

Others may hope some choices for Trump’s administration collapse under their own weight. President Obama faced several setbacks when it came to his nominees in 2009. Tom Daschle, Obama’s close friend and choice to lead the Health and Human Services Department, withdrew his nomination after reports surfaced about his failure to pay back taxes. Obama’s choice for commerce secretary, former New Mexico Gov. Bill Richardson, also withdrew in light of a federal investigation into his business dealings. Obama then nominated Republican Sen. Judd Gregg for the position, but he later withdrew, citing conflicts with the new administration over the economic policy.

Still, many in the party are eager to battle Trump’s Cabinet nominees, even if the rules are stacked in the Republicans’ favor. Democrats are “determined to hold these guys’ feet to the fire,” says strategist Jim Manley, a former top aide to Harry Reid.

Republicans have fired back, arguing that they worked with Democrats to swiftly approve President Obama’s picks, including seven nominees on Inauguration Day. The right-leaning research group America Rising Squared released a digital ad recalling Democrats urging the Senate to confirm Obama’s nominees quickly. But the nominating process has become even more politicized since then, some Democrats argue.

“In years past, members on both sides seemed to agree a president deserved to have his nominees in place, absent some serious flaw. But since 2008, Democrats believe Republicans have done everything they can to filibuster every nominee under the sun,” says Manley. “Democrats will never forget what McConnell did to [Obama Supreme Court nominee] Merrick Garland.”

Democrats also hope to expose flaws in Trump’s “drain the swamp” message by applying extra scrutiny to Mnuchin, a former Goldman Sachs executive who chaired the campaign’s finance team. Democrats are taking particular exception to his involvement in the foreclosure of thousands of homes while at the helm of OneWest Bank. The group Allied Progress is paying for two six-figure ad buys in Arizona and Nevada, targeting Republican Sens. Jeff Flake and Dean Heller, who are up for re-election in 2018 and represent states hard hit by the housing crisis, over the confirmation of Mnuchin. Economic liberals like Elizabeth Warren will likely use the Treasury hearings to highlight their own causes.

"Looking at the Cabinet, which is stacked with billionaires, corporate executives, titans of Wall Street, and those deeply embedded in Washington's corridors of power, it seems that many of [Trump’s] campaign themes are quickly being abandoned,” Schumer said on the Senate floor last week. “He said he was going to un-rig the system. So far, it still looks rigged."

Democrats are also putting pressure on DeVos, Trump’s choice to head the Education Department. A group of Democratic senators has called on her to pay $5 million in election-related fines owed by her school-choice advocacy group, All Children Matter. Additionally, the pro-campaign finance reform groups End Citizens United and Every Voice are calling on Republican senators on the Health, Education, Labor and Pensions Committee, which will vet her nomination, to recuse themselves for having received campaign contributions from the DeVos family.

But Republicans have risen to her defense. In a Washington Post op-ed, Mitt Romney wrote, “I am truly excited that someone of Betsy DeVos’s capability, dedication and absence of financial bias is willing to take an honest and open look at our schools.”

Republicans characterize Democratic opposition to Trump’s choices as playing politics, and most doubt that nominees will run into much trouble. Republican leaders also note that senators have been inclined to come around to the nominees after meeting with them. Trump’s picks made their rounds on Capitol Hill last week. Several lawmakers commented on positive meetings with Tillerson.

Foreign Relations Chairman Bob Corker said he expects Tillerson to be “overwhelmingly supported.”

The Trump team feels confident about the process. “Our legislative affairs team and others have been in constant contact both with Senate offices and staff offices. And the president-elect is in constant contact with members of the House and Senate leadership,” incoming press secretary Sean Spicer told reporters. “The nominees are getting up and answering questions and getting to know some of the senators on the committees of jurisdiction.”

White House Correspondent Alexis Simendinger and Congressional Correspondent James Arkin contributed to this report.